Transflective liquid crystal display with backlight and reflection film

ABSTRACT

A liquid crystal display includes a pair of substrates which oppose each other with a liquid crystal layer therebetween; a light source provided on the exterior of one of the substrates; and at least an organic film, a metallic reflection film, an overcoat film, an electrode layer, and an alignment film formed on the inner face of one of the substrates. Many concaves are contiguously formed on a surface of the organic film, the inner surface of each concave constituting a part of a spherical surface. The metallic reflection film has a thickness of 80 to 500 Å. A transflector and a liquid crystal display including the transflector are also disclosed.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to liquid crystal displays and,more particularly, to a technique suitable for use in a transflectiveliquid crystal display provided with a backlight and a reflection film.

[0003] 2. Description of the Related Art

[0004] Substantially all mobile phones and mobile information terminalsare now provided with liquid crystal displays, and recently, many suchmobile electronic apparatuses have been provided with transflectiveliquid crystal displays.

[0005] In general, a transflective liquid crystal display includes areflector provided on the interior or exterior of a pair of transparentsubstrates for reflecting incident light from outside and also includesa backlight at the back side thereof. The transflective liquid crystaldisplay can be used as a reflective liquid crystal display and as atransmissive liquid crystal display by switching between a reflectivemode in which solar light or an external illumination is used as a lightsource and a transmissive mode in which light from the backlight is usedas a light source.

[0006]FIG. 5 is a partial sectional view of a conventional transflectiveliquid crystal display. In a conventional transflective liquid crystaldisplay 100 shown in the drawing, a first substrate 110 and a secondsubstrate 120, which are composed of a transparent material, such asglass, are opposed to each other, and a liquid crystal layer 130 isenclosed therebetween.

[0007] An electrode layer 115 and an alignment film 116 are deposited inthat order on a surface of the first substrate 110 facing the liquidcrystal layer 130. An electrode layer 125 and an alignment film 126 aredeposited in that order on a surface of the second substrate 120 facingthe liquid crystal layer 130.

[0008] A polarizer 118 is provided on another surface of the firstsubstrate 110 opposite to the liquid crystal layer 130 (i.e., the outersurface of the substrate 110), and a reflector 119 having a reflectionfilm 119 a composed of a metal is provided on the outer surface thereofsuch that the reflection film 119 a faces the polarizer 118. A polarizer128 is provided on the outer surface of the second substrate 120. Abacklight 105 for transmissive display is provided on the back of theliquid crystal display 100.

[0009] The transflective liquid crystal display 100 having the structuredescribed above is used, for example, as a display area of a mobilephone. When there is sufficient external light, the transflective liquidcrystal display 100 operates in the reflective mode in which thebacklight 105 is off, and in an environment where there is insufficientexternal light, it operates in the transmissive mode in which thebacklight 105 is on.

[0010] However, in the transflective liquid crystal display 100, sincethe reflector 119 is placed on the exterior of the substrate 110, lightentering the liquid crystal display 100 from outside must pass throughtwo substrates, 110 and 120, and two polarizers, 118 and 128, beforebeing reflected by the reflector 119. Therefore, the propagation loss oflight is increased, and it is not possible to obtain satisfactorybrightness when the transflective liquid crystal display 100 is used asa reflective liquid crystal display.

[0011] On the other hand, in the transmissive mode in which the liquidcrystal display 100 is used as a transmissive liquid crystal display,although the reflector 119 must transmit light from the backlight 105,the thickness of the reflection film 119 a is usually set at 1,000 to1,500 Å in order to increase the reflectance of light. That is, poresare made in the reflection film 119 a in order to transmit light.

[0012] However, in the method in which light from the backlight 105 istransmitted by providing the pores in the reflection film 119 a, if theaperture ratio of the pores of the reflection film 119 a is increased,the reflectance of the reflection film 119 a is decreased, therebydecreasing brightness in the reflective mode. Therefore, it is notpossible to sufficiently increase the aperture ratio, and satisfactorilybright display is not obtained when the backlight 105 is lit.

[0013] In order to solve the problems described above, a structure isdisclosed, in which a reflector is placed between two substratesconstituting a liquid crystal display so that the number of layers ofsubstrates and polarizers through which light passes before reaching thereflector is decreased, and, by suppressing the propagation loss oflight in the reflective mode, brighter reflective display can beobtained. By using such a structure, since display brightness in thereflective mode is ensured where possible, it is believed thatbrightness in the transmissive mode can be increased by decreasing thethickness of the reflection film for reflecting light to approximately300 Å, but brightness in the reflective mode is slightly sacrificed.

[0014] However, even if such a structure is used, although the displaybrightness in the transmissive mode is improved, the brightness in thereflective mode is the same as that of the liquid crystal display 100.If the thickness of the reflection film is increased to a certain degreeby giving a high priority to the brightness in the reflective mode, thebrightness in the transmissive mode becomes insufficient.

[0015] As described above, a transflective liquid crystal display inwhich satisfactorily bright, easily visible display is performed both inthe reflective mode and in the transmissive mode has not yet beenproduced.

SUMMARY OF THE INVENTION

[0016] It is an object of the present invention to provide atransflective liquid crystal display in which a bright display isobtained by efficiently reflecting light in the reflective mode, andalso in which bright display is obtained by satisfactorily transmittinglight in the transmissive mode in which a backlight is lit. It isanother object of the present invention to provide a transflector whichis suitable for use in such a liquid crystal display.

[0017] In one aspect of the present invention, a liquid crystal displayincludes a pair of substrates which oppose each other with a liquidcrystal layer therebetween, and a light source provided on the exteriorof the pair of substrates. At least an organic film, a metallicreflection film, an overcoat film, an electrode layer, and an alignmentfilm are formed on the inner face of one of the substrates. Manyconcaves are contiguously formed on a surface of the organic film, theinner surface of each concave constituting a part of a sphericalsurface, and the metallic reflection film has a thickness of 80 to 500Å.

[0018] In the construction of the present invention described above,since many concaves are contiguously formed on the surface of theorganic film provided with the reflection film for reflecting lightentering the liquid crystal display from outside, the inner surface ofeach concave constituting a part of a spherical surface, it is possibleto greatly improve the reflection efficiency of light in comparison tothe conventional transflective liquid crystal display. Therefore, it ispossible to improve the transmittance of the liquid crystal display bydecreasing the thickness of the metallic reflection film so that abright display is also obtained for the transmissive liquid crystaldisplay. Consequently, a bright display can be obtained both in thereflective mode and in the transmissive mode. Moreover, since brightdisplay is enabled in the reflective mode, it is not necessary to turnon the backlight even when the liquid crystal display is used in aslightly dark environment. Consequently, power consumption can bereduced in an electronic apparatus provided with the liquid crystaldisplay of the present invention.

[0019] In the liquid crystal display, preferably, the metallicreflection film has a thickness of 80 to 100 Å.

[0020] In such a construction, since the transmittance of the liquidcrystal display can be improved by decreasing the thickness of themetallic reflection film, it is possible to obtain a liquid crystaldisplay exhibiting superior visibility. Moreover, since the liquidcrystal display of the present invention has superior transmittance, itis possible to decrease the amount of light of the backlight required.Consequently, in the liquid crystal display of the present invention, itis possible to reduce the power consumption of the backlight whichconstitutes the majority of the power consumption of an electronicapparatus provided with the liquid crystal display of the presentinvention.

[0021] In the liquid crystal display, preferably, the depth of theconcaves is in the range of 0.1 to 3 μm, the inclination angle of theinner surface of each concave is in the range of −30 degrees to +30degrees, and the pitch of the adjoining concaves is in the range of 5 to50 μm.

[0022] In such a construction, since the surface configuration of theorganic film is optimized, incident light from outside is moreefficiently reflected, and thereby brighter display can be obtained.

[0023] In another aspect of the present invention, a transflectorincludes a reflection layer, the reflection layer including a metallicfilm deposited on a surface thereof, many concaves being contiguouslyformed on the surface, the inner surface of each concave constituting apart of a spherical surface. The depth of the concaves is in the rangeof 0.1 to 3 μm, the inclination angle of the inner surface of eachconcave is in the range of −30 degrees to +30 degrees, the pitch of theadjoining concaves is in the range of 5 to 50 μm, and the thickness ofthe metallic film is 80 to 500 Å.

[0024] In such a construction of the present invention, since thesurface of the reflection layer can be formed into an optimum shape,light can be reflected more efficiently. By decreasing the thickness ofthe metallic film placed on the surface of the reflection layer to thevalue described above, transmittance can be improved. Consequently, inboth cases when light is reflected and when light is transmitted, thetransflector exhibits superior characteristics.

[0025] In another aspect of the present invention, a liquid crystaldisplay includes the transflector described above.

[0026] In such a construction, it is possible to obtain a liquid crystaldisplay having superior visibility in which bright display is obtainedboth in the reflective mode and in the transmissive mode.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027]FIG. 1 is a partial sectional view of a liquid crystal display ina first embodiment of the present invention;

[0028]FIG. 2 is an enlarged perspective view showing a section includingan organic film and a metallic reflection film in a liquid crystaldisplay of the present invention;

[0029]FIG. 3 is a sectional process chart which schematically shows aprocess for forming an organic film of a liquid crystal display of thepresent invention;

[0030]FIG. 4 is a partial sectional view of a liquid crystal display ina second embodiment of the present invention; and

[0031]FIG. 5 is a partial sectional view showing a conventional liquidcrystal display.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] The embodiments of the present invention will be described withreference to the drawings. However, it is to be understood that thepresent invention is not limited to the embodiments described below.

[0033] First Embodiment

[0034]FIG. 1 is a partial sectional view which schematically shows atransflective liquid crystal display including an edge thereof in afirst embodiment of the present invention. As shown in FIG. 1, in atransflective liquid crystal display 1, a first substrate 10 and asecond substrate 20, for example, composed of a transparent glass, whichoppose each other with a liquid crystal layer 30 therebetween, areintegrally bonded to each other by a sealant 40 which is annularlyprovided in the periphery of the two substrates 10 and 20.

[0035] At the liquid crystal layer 30 side of the first substrate 10, anorganic film 11 for corrugating a reflection film 12, a metallicreflection film 12 for reflecting light entering the liquid crystaldisplay, color filters 13 for performing color display, an overcoat film14 for protecting the organic film 11 and the metallic reflection film12 as well as for planarizing the corrugation due to the organic film 11and the color filters 13, electrode layers 15 for driving the liquidcrystal layer 30, and an alignment film 16 for controlling the alignmentof liquid crystal molecules constituting the liquid crystal layer 30 aredeposited in that order. At the liquid crystal layer 30 side of thesecond substrate 20, electrode layers 25, an overcoat film 24, and analignment film 26 are deposited in that order.

[0036] A polarizer 18 is provided at a side of the first substrate 10opposite the liquid crystal layer 30 side (on the outer surface of thefirst substrate 10), and a retardation film 27 and a polarizer 28 aredeposited in that order at a side of the second substrate 20 oppositethe liquid crystal layer 30 side (on the outer surface of the secondsubstrate 20).

[0037] A backlight 5, which acts as a light source for performingtransmissive display in the transflective liquid crystal display 1, isprovided on the outer surface of the polarizer 18 of the first substrate10.

[0038] The organic film 11 corrugates the metallic reflection film 12formed thereon so that reflected light is efficiently scattered. Sincelight entering the liquid crystal display 1 is efficiently scattered bycorrugating the metallic reflection film 12, bright display is enabledin the reflective mode.

[0039]FIG. 2 is a perspective view showing a section including theorganic film 11 and the metallic reflection film 12 formed thereon. Asshown in the drawing, concaves 12A are contiguously formed on thesurface of the organic film 11 such that they share a common edge, theinner surface of each concave constituting a part of a sphericalsurface, and the metallic reflection film 12 is deposited on theconcaved surface.

[0040] Preferably, the depth of the concaves 12A is set at random in therange of 0.1 to 3 μm, the pitch of the adjoining concaves 12A is set inthe range of 5 to 50 μm, and the inclination angle of the inner surfaceof each concave 12A is in the range of −30 degrees to +30 degrees.

[0041] It is particularly important to set the inclination angle of theinner surface of each concave 12A in the range of −30 degrees to +30degrees and to arrange the pitches of the adjoining concaves 12Aplanarity at random in all directions. If the pitches of the adjoiningconcaves 12A are regular, reflected light is colored due to interferencecolors of light, and this is disadvantageous. If the inclination angleof the inner surface of the concave 12A is out of the range of −30degrees to +30 degrees, the diffusing angle of reflected light becomesexcessively large to decrease the intensity of reflection, and therebyit is not possible to obtain bright display. This is because thediffusing angle of reflected light becomes 36 degrees or more in air andthe peak of reflection intensity in the liquid crystal display isdecreased, resulting in a large total reflection loss.

[0042] If the depth of the concaves 12A exceeds 3 μm, when the concaves12A are planarized in the subsequent step, the apexes of convexes willnot be completely embedded in a planarizing film (overcoat film 14), andit is not possible to obtain desired flatness, resulting in displayunevenness.

[0043] If the pitch of the adjoining concaves 12A is less than 5 μm,constraints are imposed on the manufacture of a transfer mold used forforming the organic film 11, giving rise to problems, such as aconsiderably long processing time, not being able to form the shapewhich allows a desired reflection property, and the occurrence ofinterference of light waves. When a diamond indenter having a diameterof 30 to 100 μm, which can be practically used in practice formanufacturing the transfer mold, is used, the pitch of the adjoiningconcaves 12A is preferably set at 5 to 50 μm.

[0044] A method for forming the organic film 11 will be brieflydescribed with reference to FIG. 3.

[0045]FIG. 3 is a process chart which schematically shows a process forforming the organic film 11 of the transflective liquid crystal displayshown in FIG. 1 in this embodiment.

[0046] First, in step (A), a photosensitive resin solution, such as anacrylic resist, is applied on the first substrate 10 by spin coating orthe like, and pre-baking is then performed to form a photosensitiveresin layer 11 a.

[0047] Next, in step (B), a transfer mold 19 which includes a corrugatedsurface 19 a and a flat surface 19 b in the periphery thereof is pressedagainst the surface of the photosensitive resin layer 11 a so that theshape of the corrugated surface 19 a of the transfer mold 19 istransferred to the surface of the photosensitive resin layer 11 a.

[0048] Additionally, in order to manufacture the transfer mold 19, adiamond indenter is pressed to the surface of a base material for amatrix having a planar surface composed of brass, stainless steel, toolsteel, or the like to form the surface configuration shown in FIG. 2,and thereby the matrix for transferring is formed. The transfer mold 19is molded from a silicon resin or the like using the matrix fortransferring. The transfer mold 19 has corrugation which is the reverseof the surface configuration of the concaves 12A shown in FIG. 2.

[0049] Next, in step (C), a section corresponding to the flat surface 19b in the periphery of the transfer mold 19 on a back surface 10 a of thefirst substrate 10 is covered by a photomask 21. The back surface 10 aof the first substrate 10 is then irradiated with light 22, such asultraviolet light (g-line, h-line, or i-line) so that the photosensitiveresin layer 11 a is cured.

[0050] In step (D), the photomask 21 is removed from the first substrate10 and the transfer mold 19 is detached from the photosensitive resinlayer 11 a. At this stage, since the section corresponding to the flatsurface 19 b in the photosensitive resin layer 11 a is masked by thephotomask 21, it is not cured and is removed together with the transfermold 19 when the transfer mold 19 is detached. Development, and rinsingusing deionized water are performed, and firing is then performed usinga heating medium, such as a heating oven, or a hot plate.

[0051] The organic film 11 having the corrugated surface is therebyformed on a predetermined region on the first substrate 10.

[0052] By forming the organic film 11 on the region excluding theperiphery of the substrate 10, it is possible to cover the organic film11 up to the edge by the overcoat film 14 to be formed later. Thereby,the organic film 11 is prevented from being brought into contact withoutside air, and degradation of the organic film 11 due to moisture canbe avoided.

[0053] The metallic reflection film 12 reflects/scatters light enteringthe liquid crystal layer 30 so that bright display is obtained, and isformed on the corrugation of the organic film 11. Preferably, themetallic reflection film 12 is composed of a metallic material having ahigh reflectance, such as Al or Ag. The metallic reflection film 12 maybe formed by deposition, such as sputtering or vacuum deposition, usingthe metallic material.

[0054] Since the metallic material, such as Al or Ag, does notnecessarily have good adhesion to the substrate 10 composed of glass, ifa part of the metallic reflection film 12 is formed between the overcoatfilm 14 and the substrate 10, separation of the film may occur.

[0055] Therefore, when the metallic reflection film 12 is formed,preferably, the periphery of the substrate 10 in which the organic film11 is not formed is covered by a mask, and the mask is removed after themetallic reflection film 12 is formed so that the film of the metallicmaterial is not deposited on the first substrate 10.

[0056] Preferably, the metallic reflection film 12 has a thickness of 80to 500 Å. If the thickness is less than 80 Å, display becomes darker inthe reflective mode because the reflectance of light by the metallicreflection film 12 is too insignificant. If the thickness is larger than500 Å, display becomes dark in the transmissive mode because thetransmittance of the metallic reflection film 12 is decreased.

[0057] More preferably, the metallic reflection film 12 has a thicknessof 80 to 200 Å. If the thickness of the metallic reflection film 12 isin such a range, since bright display is enabled in the transmissivemode, the difference in brightness between the transmissive mode and thereflective mode can be decreased. Therefore, when the transflectiveliquid crystal display is used by switching between the two operationalmodes, the visibility of the display can be improved.

[0058] Most preferably, the metallic reflection film 12 has a thicknessof 80 to 100 Å (i.e., 90 Å±10 Å). In such a range, brightness in thereflective mode can be maintained and considerably superior brightnessis enabled in the transmissive mode.

[0059] As described above, in the liquid crystal display 1 of thepresent invention, although the metallic reflection film 12 with athickness which is considerably small compared to the conventionalliquid crystal display is used, display can be performed withsatisfactory brightness in the reflective mode, and because of thedecrease in the thickness of the metallic reflection film 12, remarkablybright display is enabled in the transmissive mode compared to theconventional liquid crystal display.

[0060] The reason for the above is due to the surface configuration ofthe organic film 11 described above. That is, the reflectance itself ofthe metallic reflection film 12 is decreased if the thickness of themetallic reflection film 12 is decreased in order to increase thetransmittance. However, bright display is enabled in the transmissivemode without greatly losing the display brightness in the reflectivemode by forming concaves contiguously on the surface of the organic film11, the inner surface of each concave constituting a part of a sphericalsurface, so that the reflection efficiency of light by the metallicreflection film 12 is maximized.

[0061] In the liquid crystal display 1 of the present invention, if thethickness of the metallic reflection film 12 is set in the range of 80to 100 Å, remarkably bright display is enabled in the transmissive mode.A bright display is achieved not only because of the improvement intransmittance due to a large decrease in the thickness of the metallicreflection film 12, but also because of the advantages of using thesurface configuration of the organic film 11. That is, as shown in FIG.2, since the inner surface of each concave 12A formed on the surface ofthe organic film 11 is spherical, the lens effect acts on light enteringthe organic film 11 from the substrate 10 side, and light from thebacklight 5 passing through the organic film 11 is amplified, resultingin a remarkably bright display.

[0062] A plurality of strip electrode layers 15 composed of atransparent conductive film such as indium tin oxide (ITO) is arrayed onthe overcoat film 14. The individual electrode layers 15 are connectedto an external drive circuit (not shown in the drawing) and drivesliquid crystal molecules constituting the liquid crystal layer 30.Similarly, a plurality of strip electrode layers 25 composed of atransparent conductive film such as ITO is arrayed on the substrate 20.The individual electrode layers 25 are connected to an external drivecircuit. The electrode layers 15 and the electrode layers 25 aredisposed so as to be orthogonal to each other when viewed from the top,and thus the liquid crystal display 1 is of a passive matrix type.

[0063] Although the liquid crystal display of the passive matrix typehas been described above, the present invention is not limited theretoand is also applicable to a liquid crystal display of an active matrixtype. In such a case, for example, after a transparent organic filmhaving the surface configuration described above is formed above orbelow pixel electrodes constituting pixels, a metallic reflection filmcomposed of Al, Ag, or the like is formed on the organic film at athickness of 80 to 500 Å.

[0064] Second Embodiment

[0065] In the first embodiment, the metallic reflection film 12 forreflecting light entering from outside is disposed between the substrate10 and the substrate 20. In contrast, in a second embodiment of thepresent invention, a reflector is provided on the exterior of twosubstrates which sandwich a liquid crystal layer.

[0066]FIG. 4 is a partial sectional view which schematically shows aliquid crystal display 2 in the second embodiment of the presentinvention. As shown in FIG. 4, in the liquid crystal display 2, a firstsubstrate 60 and a second substrate 70, for example, composed of atransparent glass, which oppose each other with a liquid crystal layer80 therebetween, are integrally bonded to each other by a sealant 90which is annularly provided in the periphery of the substrates 60 and70.

[0067] At the liquid crystal layer 80 side of the first substrate 60,electrode layers 65 for driving the liquid crystal layer 80, and analignment film 66 for controlling the alignment of liquid crystalmolecules constituting the liquid crystal layer 80 are deposited. At theliquid crystal layer 80 side of the second substrate 70, electrodelayers 75, an overcoat film 74, and an alignment film 76 are depositedin that order.

[0068] A polarizer 68 is provided at a side of the first substrate 60opposite the liquid crystal layer 80 side (on the outer surface of thefirst substrate 60), and a retardation film 77 and a polarizer 78 aredeposited in that order at a side of the second substrate 70 oppositethe liquid crystal layer 80 side (on the outer surface of the secondsubstrate 70).

[0069] A transflector 3 in accordance with the present invention isplaced on the outer surface (lower surface) of the polarizer 68 of thefirst substrate 60 so that a reflection film 3 a faces the polarizer 68.An adhesive 4 composed of a material which does not adversely affect therefractive index of light, such as glycerol, is filled between thepolarizer 68 and the transflector 3.

[0070] Although not shown in the drawing, a color filter layers may beformed by printing or the like between the substrate 60 and theelectrode layers 65 so that the liquid crystal display performs colordisplay.

[0071] A backlight 50, which acts as a light source for performingtransmissive display in the transflective liquid crystal display 2, isprovided on the back of the transflective liquid crystal display 2 (atthe outer surface of the first substrate 60).

[0072] The transflector 3 shown in FIG. 4 enables bright display andwidens the angle of view by efficiently reflecting and diffusingincident light. In order to form the reflection film 3 a, a surfaceconfiguration which is the same as that of the organic film 11 in thefirst embodiment shown in FIG. 2, (i.e., the configuration in whichconcaves 12 are contiguously formed, the inner surface of each concaveconstituting a part of a spherical surface), is transferred to thesurface of a flat resin base (a base for the reflector) composed of aphotosensitive resin or the like formed on a substrate composed of atransparent glass or the like, and a thin film composed of Al or Ag isdeposited thereon by vapor deposition, printing, or the like.

[0073] Additionally, as a material for the substrate described above, atransparent material having a high transmittance, such as glass, may beused without problems, or a flexible film composed of a resin may beused. In some cases, the substrate may not be provided. Additionally,the transflector 3 can be fabricated by substantially the same method asthat for the organic film 11 in the first embodiment shown in FIG. 3.

[0074] The surface configuration of the transflector 3 is the same asthat for the organic film 11 shown in FIG. 2. Preferably, the depth ofthe concaves formed on the surface of the transflector 3 is set atrandom in the range of 0.1 to 3 μm, the pitch of the adjoining concavesis set at random in the range of 5 to 50 μm, and the inclination angleof the inner surface of each concave is set in the range of −30 degreesto +30 degrees. The reasons for this are the same as those described inthe first embodiment. By forming the concaves so as to satisfy the aboveconditions, the reflection efficiency of the transflector 3 can beincreased.

[0075] The reflection film 3 a is formed on the surface of thetransflector 3, and it reflects and scatters incident light. Thereflection film 3 a preferably has a thickness of 80 to 500 Å, the sameas the metallic reflection film 12 in the first embodiment. The reasonfor this is the same as that described in the first embodiment, and bysetting the thickness in the above range, bright display is also enabledin the transmissive mode. In particular, if the thickness is set in therange of 80 to 100 Å (i.e., 90 Å±10 Å), remarkably bright display isenabled.

[0076] In the liquid crystal display 2 provided with the transflector 3having the structure described above, the same as the liquid crystaldisplay 1 in the first embodiment, brighter, more easily visible displayis performed both in the reflective mode and in the transmissive modecompared to the conventional liquid crystal display. This is because ofthe improvement in the reflection efficiency of light due to the surfaceconfiguration of the transflector 3 and because of the improvement intransmittance due to a significantly small thickness of 80 to 300 Å ofthe reflection film 3 a formed on the transflector 3.

[0077] Since the transflector 3 is an exterior type which is placed onthe exterior of the substrates constituting the liquid crystal display,the transflector 3 can be mounted on a transmissive liquid crystaldisplay without problems, and it is possible to produce a transflectiveliquid crystal display in which bright display is performed both in thereflective mode and in the transmissive mode. Therefore, by using thetransflector 3 of the present invention, it is possible to manufacture atransflective liquid crystal display without changing the structure ofthe liquid crystal device except a reflector, thereby minimizing thecost for changing the manufacturing process.

[0078] Although the present invention is applied to a passive matrixliquid crystal display in the second embodiment, the present inventionis also applicable to a three-terminal type (thin-film transistor: TFT)active matrix liquid crystal display and a two-terminal type activematrix liquid crystal display.

[0079] By applying the present invention to such active matrix liquidcrystal displays, it is possible to obtain liquid crystal displays whichprovide a high-speed response and a wide angle of view and alsosatisfactory visibility in both cases when the backlight is on and whenthe backlight is off.

[0080] The present invention will be described in more detail based onthe examples. However, it is to be understood that the present inventionis not limited the examples described below.

EXAMPLE 1

[0081] An organic film composed of a photosensitive resin having athickness of 2 μm was formed on a glass substrate with a thickness of0.7 mm. An aluminum film, as a metallic reflection film, was depositedon the organic film at a thickness of 90 Å, and an overcoat film wasdeposited at a thickness of 300 Å so as to cover the organic film andthe metallic reflection film. Electrode layers and an alignment filmwere deposited thereon in that order, and a substrate for a liquidcrystal display was thereby prepared. With respect to the surfaceconfiguration of the organic film, concaves were formed on the surfaceof the organic film so as to satisfy the following conditions: the depthof the concaves was in the range of 0.6 to 1.2 μm, the inner surface ofeach concave constituting a part of a spherical surface; the inclinationangle of the inner surface of each concave was in the range of −8degrees to +8 degrees; and the pitch of the adjoining concaves was inthe range of 26.5 to 36.5 μm.

[0082] The substrate for the liquid crystal display and a countersubstrate provided with electrode layers, an alignment film, etc., whichwas prepared separately, were integrally bonded to each other by asealant, and a liquid crystal was then injected between the twosubstrates. A backlight was placed on the exterior of the substrate forthe liquid crystal display, and a transflective liquid crystal displaywas thereby fabricated.

EXAMPLES 2 TO 5

[0083] Transflective liquid crystal displays having the same structureas that of Example 1 were fabricated, except that aluminum films, asmetallic reflection films, with the thicknesses described below wereformed. Thickness of Reflection Film EXAMPLE 2 100 Å EXAMPLE 3 150 ÅEXAMPLE 4 200 Å EXAMPLE 5 300 Å

COMPARATIVE EXAMPLES 1 TO 3

[0084] Transflective liquid crystal displays having the same structureas that of Example 1 were fabricated, except that aluminum films asmetallic reflection films with thicknesses described below were formed.Thickness of Reflection Film COMPARATIVE   75 Å EXAMPLE 1 COMPARATIVE  325 Å EXAMPLE 2 COMPARATIVE 1,000 Å EXAMPLE 3

EXAMPLE 6

[0085] An organic film composed of a photosensitive resin having athickness of 2 μm was formed on a glass substrate with a thickness of0.5 mm. Concaves were formed on the surface of the organic film so as tosatisfy the following conditions: the depth of the concaves was in therange of 0.6 to 1.2 μm, the inner surface of each concave constituting apart of a spherical surface; the inclination angle of the inner surfaceof each concave was −8 degrees to +8 degrees; and the pitch of theadjoining concaves was in the range of 26.5 to 36.5 μm. An aluminum filmwith a thickness of 90 Å, as a reflection film, was deposited on theorganic film, and thereby a transflector was fabricated.

[0086] The transflector was bonded to the back of a transmissive liquidcrystal display with an adhesive comprising glycerol therebetween sothat the reflection film faced the liquid crystal display, and abacklight was placed on the outside of the transflector. A transflectiveliquid crystal display was thereby fabricated.

EXAMPLES 7 TO 10

[0087] Transflectors having the same structure as that of Example 6 andtransflective liquid crystal displays using the transflectors werefabricated, except that aluminum films, as reflection films, with thethicknesses described below were formed. Thickness of Reflection FilmEXAMPLE 7 100 Å EXAMPLE 8 150 Å EXAMPLE 9 200 Å EXAMPLE 10 300 Å

COMPARATIVE EXAMPLES 4 TO 6

[0088] Transflectors having the same structure as that of Example 6 andtransflective liquid crystal displays using the transflectors werefabricated, except that aluminum films, as reflection films, withthicknesses described below were formed. Thickness of Reflection FilmCOMPARATIVE   75 Å EXAMPLE 4 COMPARATIVE   325 Å EXAMPLE 5 COMPARATIVE1,000 Å EXAMPLE 6

[0089] With respect to the transflective liquid crystal displaysfabricated in Examples 1 to 10 and Comparative Examples 1 to 6, displaybrightness was evaluated both in the reflective mode in which thebacklight was off and in the transmissive mode in which the backlightwas on. The evaluation results were classified according to the fourlevels described below, and in addition to evaluations in the reflectivemode and in the transmissive mode, comprehensive evaluations resultingtherefrom were also made.

[0090] Evaluation Results

[0091] A Remarkably bright and easily visible

[0092] B Bright and easily visible

[0093] C Slightly dark

[0094] D Insufficiently bright but visible

[0095] First, with respect to the liquid crystal displays havingreflection films inside in Examples 1 to 5 and Comparative Examples 1 to3, the evaluation results are shown in a table below. As shown in thetable, with respect to the liquid crystal displays in Examples 1 and 2,a remarkably bright and easily visible display was obtained both in thereflective mode and in the transmissive mode. With respect to the liquidcrystal displays in Examples 3 to 5, brightness in the transmissive modewas slightly inferior compared to Examples 1 and 2, and accordingly, adecrease in visibility was observed. With respect to the liquid crystaldisplay in which the thickness of the reflection film was 300 Å inExample 5, there was a difference in display brightness between thetransmissive mode and the reflective mode, and although displaybrightness was sufficient for use, it was slightly difficult to see thedisplay when the liquid crystal display was used while switching betweenthe transmissive mode and the reflective mode. Additionally, withrespect to the brightness in the transmissive mode in Examples 3 to 5,the liquid crystal display in Example 3 was brightest, the display inExample 5 was darkest, and brightness in Example 4 was between these tworesults.

[0096] In contrast, in the liquid crystal display in Comparative Example1, display in the reflective mode was slightly dark, and in the liquidcrystal display in Comparative Example 2, display in the transmissivemode was slightly dark, and therefore, display was significantly moredifficult to see compared to the liquid crystal displays in Examples 1to 5. In the liquid crystal display in Comparative Example 3, sincesubstantially no light was transmitted, display in the transmissive modewas significantly inferior. Thickness of Evaluation EvaluationReflection of of Comprehensive film Reflection Transmittance EvaluationExample 1   90 Å A A A Example 2   100 Å A A A Example 3   150 Å A B BExample 4   200 Å A B B Example 5   300 Å A B B Comparative   75 Å C A CExample 1 Comparative   325 Å A C C Example 2 Comparative 1,000 Å A D DExample 3

[0097] Next, with respect to the transflective liquid crystal displaysprovided with the transflectors on the exterior thereof in Examples 6 to10 and Comparative Examples 4 to 6, the evaluation results are shown ina table below. Similarly to the evaluation results of the liquid crystaldisplays having reflection films inside, with respect to the liquidcrystal displays in Examples 6 and 7, in which the thickness of thereflection film was 90 Å and 100 Å, respectively, brightest and easilyvisible display was obtained, and with respect to the liquid crystaldisplays in Examples 8 to 10, brightness was slightly low compared toExamples 6 and 7. However, with respect to the liquid crystal display inExample 10 in which the thickness of the reflection film was 300 Å,similar to the liquid crystal display in Example 5, there was adifference in brightness depending on the operation modes, and it wasslightly difficult to see the display when the liquid crystal displaywas used while switching between the transmissive mode and thereflective mode.

[0098] In Comparative Examples 4 and 6, brightness was insufficient inthe reflective mode and in the transmissive mode, respectively, andalso, since the transflectors were provided outside, brightness tendedto be more insufficient than the liquid crystal displays havingreflection films inside in Comparative Examples 1 and 2. With respect tothe liquid crystal display in Comparative Example 6, brightness wasinsufficient in the transmissive mode, the same as in the ComparativeExample 3. Thickness of Evaluation Evaluation Reflection of ofComprehensive film Reflection Transmittance Evaluation Example 6   90 ÅA A A Example 7   100 Å A A A Example 8   150 Å A B B Example 9   200 ÅA B B Example 10   300 Å A B B Comparative   75 Å C A C Example 4Comparative   325 Å A C C Example 5 Comparative 1,000 Å A D D Example 6

[0099] In the method in which the degree of brightness was classifiedaccording to four levels, although the brightness of the liquid crystaldisplays having reflection films inside in Examples 1 and 2 and thebrightness of the liquid crystal displays provided with transflectors onthe exterior thereof in Examples 6 and 7 were evaluated as “A”, abrighter display was obtained in the liquid crystal displays whereinlight pass through fewer substrates in Examples 1 and 2 compared to theliquid crystal displays in Examples 6 and 7, respectively, both in thereflective mode and in the transmissive mode.

[0100] The liquid crystal displays in Examples 1 to 10 provided displaybrightness sufficient for practical use.

What is claimed is:
 1. A liquid crystal display comprising: a pair ofsubstrates which oppose each other with a liquid crystal layertherebetween; a light source provided on the exterior of one of thesubstrates; and at least an organic film, a metallic reflection film, anovercoat film, an electrode layer, and an alignment film formed on theinner face of one of the substrates, wherein many concaves arecontiguously formed on a surface of the organic film, the inner surfaceof each concave constituting a part of a spherical surface, and themetallic reflection film has a thickness of 80 to 500 Å.
 2. A liquidcrystal display according to claim 1, wherein the metallic reflectionfilm has a thickness of 80 to 100 Å.
 3. A liquid crystal displayaccording to claim 1, wherein the depth of the concaves is in the rangeof 0.1 to 3 μm, the inclination angle of the inner surface of eachconcave is in the range of −30 degrees to +30 degrees, and the pitch ofthe adjoining concaves is in the range of 5 to 50 μm.
 4. A transflectorcomprising: a base having many concaves contiguously formed on a surfacethereof, the inner surface of each concave constituting a part of aspherical surface; and a metallic reflection film formed on the surfaceof the base, wherein the depth of the concaves is in the range of 0.1 to3 μm, the inclination angle of the inner surface of each concave is inthe range of −30 degrees to +30 degrees, the pitch of the adjoiningconcaves is in the range of 5 to 50 μm, and the reflection film has athickness of 80 to 500 Å.
 5. A transflector according to claim 4,wherein the reflection film has a thickness of 80 to 100 Å.
 6. A liquidcrystal display comprising a transflector according to claim 4.